Crews are cleaning the cyclorama in Gettysburg.In 2009, the painting, which depicts the battle, was installed at the new visitor's center.The exhibit will remain open during the month-long project.Click here for a slideshow of the crews at work.Slideshow: Gettysburg unlocked, step inside the Union general's headquarters

GETTYSBURG, Pa. —

Crews are cleaning the cyclorama in Gettysburg.

In 2009, the painting, which depicts the battle, was installed at the new visitor's center.